Question

I have a table like

col1 col2 col3
abc  123  A
abc  345  B
def  567  A
ghi  890  B

I want to have the data in one row related to an element. Col3 is the discriminator element. Only the ‘A’ and ‘B’ rows are related. Result should look like

col1 col2A col2B
abc  123   345
def  567   --
ghi  --    890

How can i do that??

Answer 1

That might not be case to use self join. This will work for the data you posted:

select 
    col1,
    max(case col3 when 'A' then col2 else null end) col2A,
    max(case col3 when 'B' then col2 else null end) col2B
from YourTable
group by col1

Of course, if you have data like below, it would fail:

col1 col2 col3
abc  123  A
abc  345  B
abc  567  A

Then again, not only the query would fail, but your whole business rule would fail if you have data like this.